Chip interacts with diverse homeodomain proteins and potentiates Bicoid activity in vivo

Abstract

The Drosophila protein Chip potentiates activation by several enhancers and is required for embryonic segmentation. Chip and its mammalian homologs interact with and promote dimerization of nuclear LIM proteins. No known Drosophila LIM proteins, however, are required for segmentation, nor for expression of most genes known to be regulated by Chip. Here we show that Chip also interacts with diverse homeodomain proteins using residues distinct from those that interact with LIM proteins, and that Chip potentiates activity of one of these homeodomain proteins in Drosophila embryos and in yeast. These and other observations help explain the roles of Chip in segmentation and suggest a model to explain how Chip potentiates activation by diverse enhancers.

Roles of the sister chromatid cohesion apparatus in gene expression, development, and human syndromes

“…Reducing Nipped-B dosage would slow the rate of cohesin mobilization, thus hindering activation. It is unknown how cohesin would hinder enhancer-promoter communication, but one possibility is similar to that proposed for the gypsy transposon insulator, in which the insulator blocks a spread of homeoprotein binding between the enhancer and promoter (Dorsett 1999;Gause et al 2001;Torigoi et al 2000). …”

Dynamic spatiotemporal expression of LIM genes and cofactors in the embryonic and postnatal cerebral cortex

“…Support for the latter scenario comes from studies on Drosophila segmentation, where CHIP, the Drosophila homolog of Clim2, appears to have broad functions beyond interacting with LIM proteins (Morcillo et al, 1997). CHIP is required for embryonic segmentation, and interacts with diverse homeodomain proteins by means of residues distinct from those that interact with LIM domains (Torigoi et al, 2000).…”

LMO4 can interact with Smad proteins and modulate transforming growth factor-β signaling in epithelial cells

“…LMOs interact strongly with transcriptional coregulators referred to as Co-factors of LIM domains (Clims)/LIM domain-binding proteins (Ldb)/nuclear LIM interactors (Nli) (Agulnick et al, 1996;Jurata et al, 1996;Bach et al, 1997Bach et al, , 1999Visvader et al, 1997;Matthews and Visvader, 2003). The Clims also interact with the LIM domains of LIM homeodomain proteins as well as with some transcription factors that lack LIM domains (Torigoi et al, 2000;Matthews and Visvader, 2003). Clims, which interact with transcription factors via the C-terminus, are thought to coordinate the assembly of large multiprotein transcriptional complexes through their N-terminally located dimerization domains (Matthews and Visvader, 2003).…”